One form of post anchor according to the prior art comprises a base with four upstanding sidewalls and means such as screws to attach the post anchor to a post within the cavity defined by the sidewalls. Such a post anchor is described in U.S. Pat. No. 6,729,089 issued May 4, 2004 to Spragg.
One difficulty encountered with prior art post anchors is that water, such as rainwater, tends to run down the post and collect at the base, inside and around the post anchor cavity. Standing water or simply contact with wet ground around or inside the base of a post may cause the anchored post to rot, warp or corrode or may otherwise damage the post. Damage to the post may then destabilize any structure supported by the post.
If the post anchor is made of metal, standing water inside or around the post anchor cavity may also corrode the base and sidewalls of the post anchor, eventually leading to failure and destabilization of the supported structure. For this reason, it is known to provide a coating to the post anchor to prevent corrosion.
However, an additional difficulty with prior art post anchors is that, particularly in the case of a wood post, the post tends to absorb water and will accordingly swell, or the post may simply shorten and expand over time under the weight of the structure being supported. In both cases, the post circumference increases and exerts excess pressure from inside the cavity of the post anchor. This pressure may deform the post anchor, and may also cause any corrosion-resistant coating to crack. Under repeated swelling cycles as the post gets wet, then dries off, the cracked corrosion-resistant coating will peel or flake off and the post anchor itself will also eventually fail. Apart from the coating failure, a prior art post anchor may still fail under repeated post swelling cycles, due to fatigue in the post anchor material from the changes in pressure exerted by the post.
Exposure to elements besides water can also cause difficulties, as ultraviolet rays may cause the post anchor material to break down and eventually fail. It is therefore desirable to provide a post anchor with some protection from ultraviolet rays.
Aesthetically, it is often preferable to use a post anchor with an appearance that blends into that of the post being supported, and/or into the ground or surface on which the post anchor is mounted.
It is therefore an object of the invention to provide an improved post anchor which overcomes the above limitations and provides other desirable features.
This and other objects of the invention will be appreciated by reference to the summary of the invention and to the detailed description of the preferred embodiment that follow.